Can anyone show me how to simplify this fraction:
$$
\frac{(k + 1)((k + 1)+1)(2(k + 1)+1)}{6}\;\;.
$$
What can be factored out and so forth?
Thanks.
Answer
$$
\frac{(k+1)((k+1)+1)(2(k+1)+1)}{6}=\frac{(k+1)(k+2)(2k+3)}{6}
$$
Then if $k=2n$ you have
\begin{align*}
\frac{(k+1)(k+2)(2k+3)}{6}=&
\frac{(2n+1)(2n+2)(4n+3)}{6}\\
=&\frac{(2n+1)2(n+1)(4n+3)}{6}\\
=&\frac{(2n+1)(n+1)(4n+3)}{3}
\end{align*}
it's not so different if $k=2n+1$.
Then if you want you can consider in more detail: what if $n=2m$? And $n=2m+1$?
Enjoy!
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